1. Field of the Invention
The present invention relates to a powder developer, a developing apparatus, and an image forming apparatus.
2. Description of the Related Art
Conventional image forming apparatuses include printers, copying machines, and multi-function peripherals (MFPs). For example, a printer includes image forming units. The image forming unit includes a photoconductive drum, a charging roller, and a developing unit. The charging roller uniformly charges the surface of the photoconductive drum. An LED head illuminates the charged surface of the photoconductive drum in accordance with image data to form an electrostatic latent image on the photoconductive drum. A thin layer of toner is formed on the developing roller, and the toner on the developing roller is supplied to the electrostatic latent image to form a toner image on the photoconductive drum. The toner image is then transferred by a transfer roller onto a print medium or paper. The toner image on the print medium is then fixed into a permanent image.
JP 2003-50505A discloses a printer in which a powder developer holding apparatus or a toner cartridge is detachably attached to the image forming unit. Toner is supplied from the toner cartridge into a developing unit. The toner cartridge includes a toner discharging opening formed therein, the discharging opening being opened and closed by a shutter with an operation lever. When the lever is operated to an opening position, the shutter opens the toner discharging opening such that the toner is discharged from the toner cartridge.
The toner cartridge suffers from a problem in that the shutter may be opened with the toner discharging opening facing upward, before the toner cartridge has been attached to the image forming unit. If the shutter is opened inadvertently, foreign matter (e.g., paper particles) may enter the toner cartridge.